A CV has one purpose, which is to get you an interview; it’s a sales pitch. If you’re not getting interviews, it’s not doing its job.
If you ask five people, you’ll get five conflicting pieces of advice. I’ve seen some dreadful CVs where they’ve clearly followed some random “good advice,” like taking a 4-page CV and fitting it onto two pages by using a microscopic font and no margins or white space in order to achieve some mythical target – a CV is as long as it needs to be.
The bottom line is that what needs to be on there is “what the recruiter is looking for,” which you can tailor to an extent by cross-referencing what’s on the job spec with what’s on your CV and making it match, but there’s a large amount of crystal ball required. I’ve worked for people who have randomly thrown 50% of CVs in the bin unread because they “don’t want to employ unlucky people.”
An easy win is to make sure you’ve got the basics right. When I’m reviewing CVs I view it as the first example of the quality of your work. Spelling mistakes, poor formatting, unless I’m desperate then it’s going in the bin.
I’m not a CV service, but I’d be happy to give it a critical once-over for you.